1. Field of the Invention
This invention relates generally to data processing systems, and pertains more particularly to an optical system of this type utilizing a holographic optical element for splitting and redistributing input energy into output energy representative of certain mathematical data.
2. Description of the Prior Art
There are many mathematical operations in which an array of output data is obtained from multiplying an array of input data by a set of fixed numerical values arranged in a matrix. An example of such a vector-matrix multiplication operation would be, for instance, the performance of a discrete Fourier transform on an input vector. Here, an N element input vector would be multiplied by an M.times.N matrix to obtain an M element output vector.
Such a multiplication process can, of course, be implemented by a digital computer. Present digital computers, however, carry out operations serially so that if the vector and matrix are large, several minutes of computation might be required. Optical systems, on the other hand, can perform the requisite multiplications in parallel so that the entire operation can be completed in the nanosecond to microsecond time range.
The problem in optical computing is centered around the redistribution of the input light signals so as to provide appropriate output signals. One prior art redistribution method known to me employs fiber optics. Here, one bundle of optical fibers is illuminated by a light source whose intensity represents the value of one of the N numbers in the input vector. The fiber bundle is then divided into M sub-bundles with the number of fibers per sub-bundle being proportional to the values in one column of the matrix. The output ends of the sub-bundles are then located so that each sub-bundle illuminates one of M output detectors. The process is repeated for the other N inputs, each of which sends appropriately proportioned sub-bundles to the M output detectors.
The fiber method is limited because the number of fibers per bundle is relatively small (.apprxeq.400) so that the relative light intensity redistribution cannot be performed very accurately. The system is also difficult to replicate because each of the many fibers must be individually connected. Obviously, where vast amounts of data are to be processed, the proper connecting of numerous optical fibers proves to be very costly.